Reflective liquid crystal display apparatus

ABSTRACT

At least one exemplary embodiment is directed to a reflective liquid crystal display apparatus which includes a polarization beam splitter having a polarization split film used as both a polarizer and an analyzer; a reflective liquid crystal display device; a quarter wave plate; and a projection optical system; where the absolute value of phase difference of diffracted light generated by the reflective liquid crystal display device in a black display state is reduced by the phase difference of the quarter wave plate, and thus the amount of stray light of the diffracted light guided from the polarizing beam splitter to the projection optical system decreases.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 12/544,049, filed Aug. 19, 2009, entitled “REFLECTIVE LIQUIDCRYSTAL DISPLAY APPARATUS”, which is a divisional of U.S. patentapplication Ser. No. 11/228,612, filed Sep. 16, 2005 (and now issued asU.S. Pat. No. 7,595,848), entitled “REFLECTIVE LIQUID CRYSTAL DISPLAYAPPARATUS”, of which the contents of both applications are expresslyincorporated by reference herein in their entirety, hereby maintainingpendency. Further, the present application claims priority from JapanesePatent Application No. 2004-271469, filed Sep. 17, 2004, which is alsohereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a reflective liquid crystal displayapparatus.

2. Description of the Related Art

A configuration is discussed in U.S. Pat. No. 5,327,270 to improvecontrast of a reflective liquid crystal display apparatus. Theconfiguration includes a polarization beam splitter used as both apolarizer and an analyzer, and a quarter wave plate, where the quarterwave plate is disposed in an optical path of light exiting thepolarization beam splitter and being cast into the polarization beamsplitter again, such that the fast axis or the slow axis thereof issubstantially orthogonal to a plane containing the incident optical axisand reflected optical axis of the polarization beam splitter.

The configuration of a conventional example of a reflective liquidcrystal display apparatus is illustrated in FIG. 40.

Reference numeral 22 denotes a polarization beam splitter, 25 denotes aquarter wave plate, 34 denotes a reflective liquid crystal displaydevice, 28 denotes the fast axis of the quarter wave plate 25, 53denotes an incident light ray, 54 denotes a reflected light ray, 55denotes the polarization axis direction of the incident light ray 53being cast into the quarter wave plate 25, and 56 denotes thepolarization axis of the reflected light ray 54 which has transmittedthrough the quarter wave plate 25.

The incident light ray 53 is linear polarized light being cast into thequarter wave plate 25, and the reflected light ray 54, which has passedthrough the quarter wave plate 25 twice via the reflective liquidcrystal display device 36, is also linear polarized light. The directionbisecting the polarization direction 55 of the incident light ray 53 andthe polarization direction 56 of the reflected light ray 54 matches thefast axis 28. The polarization direction 56 of the reflected light ray54 matches the S-polarization direction of the reflected light ray 54.The polarization beam splitter is designed to not facilitatetransmission of s-polarized light, and thus there is no polarizationcomponent of the reflected light ray 54 that passes through thepolarization beam splitter 22. Thus, increasing the incident angle rangeto the polarization beam splitter 22 does not lead to reduction incontrast.

Also, a configuration is discussed in U.S. Pat. No. 6,501,523 to improvecontrast of a reflective liquid crystal display apparatus, where areflective liquid crystal display apparatus comprises a reflectiveliquid crystal display device having a liquid crystal layer held betweena transparent electrode and a reflecting electrode and a plurality ofpixel circuits for driving the liquid crystal layer, and a wave plate,with the position of the optical axis (fast axis or slow axis) of thewave plate and the polarization direction of the incident polarizedlight with respect to the wave plate being slightly offset.

The configuration of a conventional example of a reflective liquidcrystal display apparatus is illustrated in FIG. 41.

Reference numeral 101 denotes incident light, 102 denotes a polarizationbeam splitter, 103 denotes a polarizing film, 104 denotes a wave plate,105 denotes an axis parallel to the polarization plane of S-polarizedlight, 106 denotes an axis parallel to the polarization plane ofP-polarized light, 107 denotes a slow axis, 108 denotes a fast axis, 158denotes a reflective liquid crystal display device, and 124 denotes theoptical axis rotation angle of the wave plate.

Also, FIG. 42 illustrates reflectivity wavelength scattering propertiesin an arrangement where the optical axis rotation angle 124 (FIG. 41) ofthe quarter wave plate 104 is taken as a parameter with a TN (TwistedNematic) mode twist angle of 80° and voltage of 4 Vrms applied forliquid crystal black display. Now, the optical axis rotation angle 124of the quarter wave plate 104 is defined as θp, and increasing θp, witha θp=0 reference, reduces the reflectivity for liquid crystal blackdisplay. Particularly, taking note of the region around the wavelength550 nm which is the center of the visible range and which greatlyinfluences contrast, the reflectivity for liquid crystal black displayis minimal when θp=around 3, i.e., contrast is increased.

Generally, with a liquid crystal display device used in liquid crystalprojectors, pixels are arrayed in matrix fashion, and light cast intothe liquid crystal display device exhibits diffraction and interferencedue to the shape of the pixel openings.

Also, the intensity of diffracted light is inversely proportionate tothe size of the openings which have a cyclic structure, and also isproportionate to the wavelength. The pixel shape of liquid crystaldevices for liquid crystal projectors is around 10 μm×10 μm, which isfar smaller than those of direct-view liquid crystal devices used withpersonal computers, thus the diffraction phenomena occurs profusely.Moreover, diffracted (interference) light is reflected (transmitted) ata different angle from that of the specular reflection (0th ordertransmission), so phase difference error occurs due to liquid crystalwavelengths, outside the intended liquid crystal design values, passingthrough, resulting in reduced image quality of the image displayed.

The conventional art make no mention of diffracted light generated atthe reflective liquid crystal display device, and thus they have notdiscussed that abnormal polarized light due to diffracted light cannotbe controlled easily and that contrast cannot be sufficiently improved.

SUMMARY OF THE INVENTION

At least one exemplary embodiment is directed to a high-contrast liquidcrystal display apparatus that can reduce not only 0th order light fromspecular reflection off of the liquid crystal display device whendisplaying black, but also multi-order diffracted (interference) light,to facilitate a high-contrast liquid crystal display apparatus.

At least one further exemplary embodiment is directed to a reflectiveliquid crystal display apparatus, comprising: a polarization beamsplitter including a polarization split film used as both a polarizerand an analyzer; a reflective liquid crystal display device; a quarterwave plate disposed between the polarization beam splitter and thereflective liquid crystal display device; and a projection opticalsystem. The quarter wave plate can be positioned such that either theslow axis or the fast axis of the quarter wave plate is generallyparallel to the polarization axis direction of the polarization beamsplitter. Additionally the quarter wave plate can be positioned so thatthe absolute value of phase difference of diffracted light generated bythe reflective liquid crystal display device, in a black display state,is reduced by the phase difference of the quarter wave plate, and sothat the amount of stray light of the diffracted light guided from thepolarizing beam splitter to the projection optical system is decreased.

At least one exemplary embodiment is directed to a reflective liquidcrystal display apparatus, comprising: a polarization beam splitterincluding a polarization split film; a reflective liquid crystal displaydevice; a quarter wave plate disposed between the polarization beamsplitter and the reflective liquid crystal display device; and anillumination optical system for guiding a light flux from a light sourcein a converged state to the polarization beam splitter, and alsoilluminating the reflective liquid crystal display device with lightfrom the light source via the polarization beam splitter and the quarterwave plate. The optical axis of the illumination optical system can beinclined with respect to the polarization split film. A positive phasedifference can be provided to convert linear polarized light intoright-handed circling polarized light or elliptic polarized light. In atleast one exemplary embodiment, the negative phase difference can beprovided to convert linear polarized light into left-handed circlingpolarized light or elliptic polarized light. Further the phasedifference, which the reflective liquid crystal display device in ablack display state of the reflective liquid crystal display apparatus,provides to the diffracted light, occurring at the reflective liquidcrystal display device, can be positive or zero. Where, with thepolarization direction of S-polarized light defined by the optical axisof the illumination optical system and the polarization split film asthe S-polarization direction, the polarization split film, whichreceives the light flux in a converged state, has a first region whichemits light having a polarization direction inclined clockwise withrespect to the S-polarization direction as viewed from the side of thereflective liquid crystal display device, and a second region whichemits light, having a polarization direction inclined counter-clockwisewith respect to the S-polarization direction as viewed from the side ofthe reflective liquid crystal display device. The phase difference,which the reflective liquid crystal display device provides to the firstdiffracted light emitted from a point on the optical axis of thereflective liquid crystal display device and cast into the first region,is smaller than the phase difference which the reflective liquid crystaldisplay device provides to the second diffracted light emitted from apoint on the optical axis of the reflective liquid crystal displaydevice and cast into the second region. The quarter wave plate can bepositioned such that the direction of the slow axis of the quarter waveplate and the S-polarization direction are generally parallel.

At least one further exemplary embodiment is directed to a reflectiveliquid crystal display apparatus, comprising: a polarization beamsplitter including a polarization split film; a reflective liquidcrystal display device; a quarter wave plate disposed between thepolarization beam splitter and the reflective liquid crystal displaydevice; and an illumination optical system for guiding a light flux froma light source in a converged state to the polarization beam splitter.The illumination optical system can also illuminate the reflectiveliquid crystal display device with light from the light source via thepolarization beam splitter and the quarter wave plate. The optical axisof the illumination optical system can be inclined with respect to thepolarization split film. Positive phase difference can be provided toconvert linear polarized light into right-handed circling polarizedlight or elliptic polarized light. Additionally the negative phasedifference can be provided to convert linear polarized light intoleft-handed circling polarized light or elliptic polarized light. Thephase difference, which the reflective liquid crystal display device ina black display state of the reflective liquid crystal displayapparatus, provides to the diffracted light occurring at the reflectiveliquid crystal display device can be positive or zero. The polarizationdirection of S-polarized light can be defined by the optical axis of theillumination optical system and the polarization split film as theS-polarization direction. The polarization split film, which receivesthe light flux in a converged state, can have a first region which emitslight, having a polarization direction inclined clockwise with respectto the S-polarization direction as viewed from the side of thereflective liquid crystal display device, and a second region, whichemits light having a polarization direction inclined counter-clockwisewith respect to the S-polarization direction as viewed from the side ofthe reflective liquid crystal display device. The phase difference,which the reflective liquid crystal display device provides to the firstdiffracted light emitted from a point on the optical axis of thereflective liquid crystal display device and cast into the first region,can be greater than the phase difference, which the reflective liquidcrystal display device provides to the second diffracted light emittedfrom a point on the optical axis of the reflective liquid crystaldisplay device and cast into the second region. The quarter wave platecan be positioned such that the direction of the fast axis of thequarter wave plate and the S-polarization direction are generallyparallel.

At least one further exemplary embodiment is directed to a reflectiveliquid crystal display apparatus, comprising: a polarization beamsplitter having a polarization split film; a reflective liquid crystaldisplay device; a quarter wave plate disposed between the polarizationbeam splitter and the reflective liquid crystal display device; and anillumination optical system for guiding a light flux from a light sourcein a converged state to the polarization beam splitter. The illuminationoptical system also can illuminate the reflective liquid crystal displaydevice with light from the light source via the polarization beamsplitter and the quarter wave plate. The optical axis of theillumination optical system can be inclined with respect to thepolarization split film. Positive phase difference can be provided toconvert linear polarized light into right-handed circling polarizedlight or elliptic polarized light. Additionally the negative phasedifference can be provided to convert linear polarized light intoleft-handed circling polarized light or elliptic polarized light. Thephase difference, which the reflective liquid crystal display device ina black display state of the reflective liquid crystal display apparatusprovides to the diffracted light occurring at the reflective liquidcrystal display device, can be negative or zero. The polarizationdirection of S-polarized light can be defined by the optical axis of theillumination optical system and the polarization split film as theS-polarization direction. The polarization split film, which receivesthe light flux in a converged state, has a first region which emitslight having a polarization direction inclined clockwise with respect tothe S-polarization direction as viewed from the side of the reflectiveliquid crystal display device, and a second region which emits lighthaving a polarization direction inclined counter-clockwise with respectto the S-polarization direction as viewed from the side of thereflective liquid crystal display device. The phase difference, whichthe reflective liquid crystal display device provides to the firstdiffracted light emitted from a point on the optical axis of thereflective liquid crystal display device and cast into the first region,can be smaller than the phase difference which the reflective liquidcrystal display device provides to the second diffracted light emittedfrom a point on the optical axis of the reflective liquid crystaldisplay device and cast into the second region. The quarter wave plateis positioned such that the direction of the fast axis of the quarterwave plate and the S-polarization direction are generally parallel.

At least another exemplary embodiment is directed to a reflective liquidcrystal display apparatus, comprising: a polarization beam splitterhaving a polarization split film; a reflective liquid crystal displaydevice; a quarter wave plate disposed between the polarization beamsplitter and the reflective liquid crystal display device; and anillumination optical system for guiding a light flux from a light sourcein a converged state to the polarization beam splitter. The illuminationoptical system also illuminates the reflective liquid crystal displaydevice with light from the light source via the polarization beamsplitter and the quarter wave plate. The optical axis of theillumination optical system can be inclined with respect to thepolarization split film. Positive phase difference can be provided toconvert linear polarized light into right-handed circling polarizedlight or elliptic polarized light. Additionally negative phasedifference can be provided to convert linear polarized light intoleft-handed circling polarized light or elliptic polarized light. Thephase difference, which the reflective liquid crystal display device ina black display state of the reflective liquid crystal display apparatusprovides to the diffracted light occurring at the reflective liquidcrystal display device, can be negative or zero. The polarizationdirection of S-polarized light can be defined by the optical axis of theillumination optical system and the polarization split film as theS-polarization direction. The polarization split film, which receivesthe light flux in a converged state, has a first region which emitslight having a polarization direction inclined clockwise with respect tothe S-polarization direction as viewed from the side of the reflectiveliquid crystal display device, and a second region which emits lighthaving a polarization direction inclined counter-clockwise with respectto the S-polarization direction as viewed from the side of thereflective liquid crystal display device. The phase difference, whichthe reflective liquid crystal display device provides to the firstdiffracted light emitted from a point on the optical axis of thereflective liquid crystal display device and cast into the first region,can be greater than the phase difference which the reflective liquidcrystal display device provides to the second diffracted light emittedfrom a point on the optical axis of the reflective liquid crystaldisplay device and cast into the second region. The quarter wave platecan be positioned such that the direction of the slow axis of thequarter wave plate and the S-polarization direction are generallyparallel.

According to at least one exemplary embodiment, the reflective liquidcrystal display apparatus comprises a polarization beam splitter havinga polarization split film used as both a polarizer and an analyzer, anda reflective liquid crystal display device. Additionally the reflectiveliquid crystal display apparatus can include a quarter wave plate havingthe fast axis and slow axis of the optical axis disposed between thepolarization beam splitter and the reflective liquid crystal displaydevice. The positioning direction of the optical axis (fast axis andslow axis) of the quarter wave plate can be in the direction of thepolarization axis (analyzing axis) of the polarization beam splitter, sothat the polarization axis direction of the diffracted light generatedat the reflective liquid crystal display device, when displaying black,can be inclined such that stray light is reduced, thereby improvingcontrast.

Also, at least one exemplary embodiment facilitates direction of theorientation of the fast axis and slow axis of the quarter wave plate,disposed between the polarization beam splitter serving as both apolarizer and an analyzer, and the reflective liquid crystal displaydevice, facilitates reduction of the amount of stray light whendisplaying black, and the improvement of contrast.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a diagram showing the polarization axis inclinationdirection generated by a polarization split film.

FIG. 2 illustrates a diagram showing the reflecting pixel electrodestructure of a reflective liquid crystal display device.

FIG. 3 illustrates a diagram showing the amount of stray light fromdiffracted light generated by the reflective liquid crystal displaydevice.

FIG. 4 illustrates a diagram showing the optical axis adjustment angleof a quarter wave plate.

FIG. 5 illustrates a diagram showing the amount of stray light fromdiffracted light generated by the reflective liquid crystal displaydevice.

FIG. 6 illustrates a diagram showing the amount of stray light fromdiffracted light generated by the reflective liquid crystal displaydevice.

FIG. 7 illustrates a diagram showing the optical axis adjustment angleof a quarter wave plate.

FIG. 8 illustrates a diagram showing the amount of stray light fromdiffracted light generated by the reflective liquid crystal displaydevice.

FIG. 9 illustrates a diagram showing the polarization axis inclinationdirection generated by a polarization split film.

FIG. 10 illustrates a diagram showing the amount of stray light fromdiffracted light generated by the reflective liquid crystal displaydevice.

FIG. 11 illustrates a diagram showing the optical axis adjustment angleof a quarter wave plate.

FIG. 12 illustrates a diagram showing a reflective liquid crystaldisplay apparatus according to a first exemplary embodiment, with apartial enlargement of a polarization conversion element.

FIG. 13 illustrates a diagram showing polarization axis inclinationgenerated by a polarization split film in the green light path, in thefirst exemplary embodiment.

FIG. 14 illustrates a diagram showing the structure of a reflectiveliquid crystal display device according to the first exemplaryembodiment.

FIG. 15 illustrates a 0th order light phase difference contour diagramfor the reflective liquid crystal display device of the green light pathin the first exemplary embodiment.

FIG. 16 illustrates a diffracted light phase difference contour diagramfor the reflective liquid crystal display device of the green light pathin the first exemplary embodiment.

FIG. 17 illustrates a diagram showing the polarization axis inclinationangle of the polarization split film in the green light path in thefirst exemplary embodiment.

FIGS. 18A and 18B illustrate diagrams of 0th order light contrast of thereflective liquid crystal display device of the green light path in thefirst exemplary embodiment.

FIG. 19 illustrates a diagram of the inclination angle of the polarizingsplitting film to which is cast the diffracted light of the liquidcrystal display device of the green light path in the first exemplaryembodiment.

FIGS. 20A and 20B illustrate diagrams of amount of stray diffractedlight of the reflective liquid crystal display device of the green lightpath in the first exemplary embodiment.

FIG. 21 illustrates a diagram showing polarization axis inclinationgenerated by the polarization split film in the red light path in thefirst exemplary embodiment.

FIG. 22 illustrates a 0th order light phase difference contour diagramfor the reflective liquid crystal display device of the red light pathin the first exemplary embodiment.

FIG. 23 illustrates a diffracted light phase difference contour diagramfor the reflective liquid crystal display device of the red light pathin the first exemplary embodiment.

FIG. 24 illustrates a diagram showing the polarization axis inclinationangle of the polarization split film in the red light path in the firstexemplary embodiment.

FIGS. 25A and 25B illustrate diagrams of 0th order light contrast of thereflective liquid crystal display device of the red light path in thefirst exemplary embodiment.

FIG. 26 illustrates a diagram of the inclination angle of the polarizingsplitting film to which is cast the diffracted light of the liquidcrystal display device of the red light path in the first exemplaryembodiment.

FIGS. 27A and 27B illustrate diagrams of amount of stray diffractedlight of the reflective liquid crystal display device of the red lightpath in the first exemplary embodiment.

FIG. 28 illustrates a diagram showing polarization axis inclinationgenerated by the polarization split film in the blue light path in thefirst exemplary embodiment.

FIG. 29 illustrates a 0th order light phase difference contour diagramfor the reflective liquid crystal display device of the blue light pathin the first exemplary embodiment.

FIG. 30 illustrates a diffracted light phase difference contour diagramfor the reflective liquid crystal display device of the blue light pathin the first exemplary embodiment.

FIGS. 31A and 31B illustrate diagrams of 0th order light contrast of thereflective liquid crystal display device of the blue light path in thefirst exemplary embodiment.

FIG. 32 illustrates a diagram of the inclination angle of the polarizingsplitting film to which is cast the diffracted light of the liquidcrystal display device of the blue light path in the first exemplaryembodiment.

FIGS. 33A and 33B illustrate diagrams of amount of stray diffractedlight of the reflective liquid crystal display device of the blue lightpath in the first exemplary embodiment.

FIG. 34 illustrates a diagram showing a reflective liquid crystaldisplay apparatus according to a second exemplary embodiment.

FIGS. 35A and 35B illustrate diagrams showing the illumination opticalsystem according to the second exemplary embodiment.

FIG. 36 illustrates a diagram showing the incident angle intensitydistribution of the illumination optical system according to the secondexemplary embodiment.

FIGS. 37A and 37B illustrate diagrams of the distribution of stray 0thorder light of the reflective liquid crystal display device of the greenlight path in the first exemplary embodiment.

FIGS. 38A and 38B illustrate diagrams of the distribution of stray 0thorder light of the reflective liquid crystal display device of the greenlight path in the second exemplary embodiment.

FIGS. 39A and 39B illustrate diagrams of the contrast of 0th order lightof the reflective liquid crystal display device of the green light pathin the second exemplary embodiment.

FIG. 40 illustrates a diagram showing a conventional example.

FIG. 41 illustrates a diagram showing a conventional example.

FIG. 42 illustrates a diagram showing a conventional example.

FIG. 43 illustrates a diagram of the polarization state of S-polarizedlight.

FIGS. 44A and 44B illustrate diagrams of the polarization state of lightwhich has passed through a quarter wave plate.

FIGS. 45A and 45B illustrate diagrams of the polarization state oflight, of which the diffracted light phase difference is 0°, which haspassed through the quarter wave plate.

FIGS. 46A and 46B illustrate diagrams of the polarization state oflight, of which the diffracted light phase difference is 4°, immediatelybefore passing through the quarter wave plate.

FIGS. 47A and 47B illustrate diagrams of the polarization state oflight, of which the diffracted light phase difference is 4°, immediatelyafter passing through the quarter wave plate.

FIGS. 48A and 48B illustrate diagrams of the polarization state oflight, of which the diffracted light phase difference is 8°, immediatelyafter passing through the quarter wave plate.

DESCRIPTION OF THE EMBODIMENTS

The following description of exemplary embodiment(s) is/are merelyillustrative in nature and is in no way intended to limit the invention,its application, or uses.

Processes, techniques, apparatus, and materials as known by one ofordinary skill in the art may not be discussed in detail but areintended to be part of the enabling description where appropriate. Forexample a light source is mentioned and an example of a high-pressuremercury vapor lamp is given, however any light source that provides theillumination needed for the working of embodiments is intended to liewithin the scope of exemplary embodiments. Additionally the actual sizeof optical elements may not be discussed however any size from macro tonano sized optical elements are intended to lie within the scope ofexemplary embodiments (e.g., wave plates with dimensions of nanometersize, micro size, centimeter size, and meter sizes). Additionally,exemplary embodiments are not limited to visual optical photographicsystems, for example the system can be designed for use with infraredand other wavelength imaging systems. Additionally, exemplaryembodiments can be used with non-digital systems as well as digitalsystems (e.g., photographic systems using CCDs)

Note that similar reference numerals and letters refer to similar itemsin the following figures, and thus once an item is defined in onefigure, it may not be discussed for following figures.

Exemplary embodiments will now be described in detail with reference tothe drawings.

First Exemplary Embodiment

FIG. 1 illustrates a schematic diagram of a reflective liquid crystaldisplay device according to at least one exemplary embodiment.

Reference numeral 101 a denotes incident light, 102 a denotes apolarization beam splitter, 103 a a denotes a polarization split film ofthe polarization beam splitter 102 a, 104 c denotes a quarter waveplate, 104 a denotes a slow axis and 104 b denotes a fast axis, 105 adenotes a reflective liquid crystal display device, 106 a denotesincident light from the x positive direction within the xy plane, 106 bdenotes incident light from the x negative direction within the xyplane, 107 a denotes the polarization axis according to which theincident light 106 a can be inclined by the polarizing film 103 a, 107 bdenotes the polarization axis according to which the incident light 106b can be inclined by the polarizing film 103 a, the incident light axisin relation to the polarization beam splitter 102 a is the y direction,the reflection light axis is the z direction, and the directionsubstantially perpendicular to the yz plane is the x direction. Notethat the y direction and the z direction need not be orthogonal to eachother (e.g., angle of incident+angle of reflection is not equal to 90degrees). Additionally, the directions need not form a right-handedcoordinate system, for example FIG. 1 illustrates a left-handedcoordinate system where the cross product of the unit vector in thex-direction with the unit vector in the y-direction equals minus thedirection of the z-direction unit vector.

Now, the incident light 101 a reflects off of the polarization splitfilm 103 a of the polarization beam splitter 102 a, passes through thequarter wave plate 104 c, and is cast into the reflective liquid crystaldisplay device 105 a. Further, the light reflected off of the reflectiveliquid crystal display device 105 a passes through the quarter waveplate 104 c again, and then is cast into the polarization beam splitter102 a. The analyzing axis components of the polarization axisinclination 107 a and 107 b of the polarization beam splitter reanalyzed, and the transmitting axis component substantiallyperpendicular to the analyzing axis is transmitted and projected asstray light.

FIG. 2 illustrates the shape of the reflecting pixel electrodes of thereflective liquid crystal display device 105 a as viewed from thepolarization beam splitter 102 a side. Reference numeral 108 denotesreflecting pixel electrodes arrayed in matrix fashion in the x and ydirections, and 109 denotes through hole contacts for making contactbetween the reflecting pixel electrodes 108 and wiring (not shown)provided to drive the reflecting pixel electrodes 108.

Now, upon light being cast into the reflective liquid crystal displaydevice 105 a, diffracted (interference) light is generated in the xpositive direction, the x negative direction, the y positive direction,and the y negative direction, which are the directions of the array ofpixels. The diffracted (interference) light is dependent on the shape ofthe reflective pixel electrodes and the wavelength of the incidentlight. The diffracted light traveling in the x positive direction iscast into the region of the polarizing axis 107 a of the polarizationsplit film 103 a inclined clockwise, the polarizing axis 107 a directioncomponent is analyzed, and the component substantially perpendicular tothe polarizing axis 107 a direction is transmitted. The diffracted lighttraveling in the x negative direction is cast into the region of thepolarizing axis 107 b of the polarization split film 103 a inclinedcounter-clockwise. The polarizing axis 107 b direction component isanalyzed, and the component substantially perpendicular to thepolarizing axis 107 b direction is transmitted. On the other hand, withregard to incident or reflected light from within the yz plane, thepolarization axis direction of the polarization split film 103 a isaligned in the x direction, so the x direction component of diffractedlight traveling in the y positive direction or y negative direction isanalyzed by the polarization split film 103 a, and the componentsubstantially perpendicular to the x direction (i.e., the y direction)is transmitted.

Now, let us consider a case where a beam, which reflects off of thepolarization split film 103 a with S-polarization in the z-axialdirection, which is the optical axis direction of the incident light 101a, is cast into the quarter wave plate 104 c and reflective liquidcrystal display device. The beam which has reflected off of thepolarization split film 103 a with S-polarization is subjected to thephase effects of the quarter wave plate 104 c while being transmittedtherethrough, and is cast into the reflective liquid crystal displaydevice 105 a, where diffracted light is generated in the x and y axialdirections (four directions) due to the shape of the pixel electrodes ofthe reflective liquid crystal display device 105 a.

First, let us discuss diffracted light generated in the x positivedirection and x negative direction. FIG. 3 illustrates the calculationresults of the sum of the amount of stray light due to diffracted lightof arbitrary phase differences being cast in the directions of thepolarization axis 107 a inclined 5° in the clockwise direction and thepolarization axis 107 b inclined 5° in the counter-clockwise direction.The “X positive direction diffracted light phase difference (degrees)”in FIG. 3 means the phase difference which the reflective liquid crystaldisplay device gives to the incident light. FIG. 3 illustrates phasedifference cases of 0 degrees (indicated by circles), 4 degrees(indicated by x marks), 8 degrees (indicated by triangles), 12 degrees(indicated by squares), and 16 degrees (indicated by dashes). In eachcase, the intensity of the diffracted light is 1, and the phasedifference of the quarter wave plate 104 c is 90°. Also, “phasedifference” in exemplary embodiments can be determined from theintensity ratio between the major axis and minor axis of ellipticpolarized light in the polarization state, i.e., can be defined suchthat the phase difference of linear polarized light is 0° (or) 180° andthe phase difference of circling polarized light where the major axisintensity and minor axis intensity are equal is 90° (or) 270°.

Also, the sum of stray diffracted light in FIG. 3 is the minimal valueobtained by arbitrarily rotating the optical axis (slow axis) of thequarter wave plate 104 c within the xy plane. FIG. 4 (the same as FIG. 3regarding the X positive direction diffracted light phase difference)illustrates the optical axis rotation angle of the quarter wave plate104 c, where the sum of stray diffracted light is minimal. Now, theoptical axis rotation direction of the quarter wave plate 104 c can bedefined such that the clockwise direction as viewed from the reflectiveliquid crystal display device 105 a is positive, and thecounter-clockwise direction is negative. Also, FIG. 5 (the same as FIG.3 regarding the X positive direction diffracted light phase difference,which will also hold true for FIGS. 6, 7, 8, 10, 11, 15, 17, 22, 24, 29,36, 37A, 37B, 38A, and 38B) illustrates the amount of stray light withrespect to the difference between the phase difference of the x negativedirection diffracted light and the phase difference of the x positivedirection diffracted light based on the calculated value shown in FIG.3.

Next, let us discuss diffracted light generated in the y positivedirection and y negative direction. FIG. 6 illustrates the calculationresults of the sum of the amount of stray light due to diffracted lightof arbitrary phase differences being cast in the y positive directionand y negative direction within the yz plane. The sum of straydiffracted light in FIG. 6 is the minimal value obtained by arbitrarilyrotating the optical axis (slow axis) of the quarter wave plate 104 cwithin the xy plane. FIG. 7 illustrates the optical axis rotation angleof the quarter wave plate 104 c, where the sum of stray diffracted lightis minimal. Also, FIG. 8 illustrates the amount of stray light withrespect to the difference between the phase difference of the x negativedirection diffracted light and the phase difference of the y positivedirection diffracted light.

Referring to FIG. 5, in the event that the y negative directiondiffracted light phase difference minus the y positive directiondiffracted light phase difference is zero or greater, i.e., in the eventthat the phase difference of the diffracted light cast into thepolarization axis 107 a inclined clockwise (diffracted light proceedingin the y positive direction) is smaller than the phase difference of thediffracted light cast into the polarization axis 107 b inclinedcounter-clockwise (diffracted light proceeding in the y negativedirection), the amount of stray diffracted light is small.

Also, referring to FIG. 8, the sum of the amount of stray diffractedlight is such that the y negative direction diffracted light phasedifference minus the y positive direction diffracted light phasedifference is symmetrically balanced on zero, and is independent of themagnitude of phase difference of each case of diffracted lightprocessing in the y positive direction and y negative direction.

In the event that the phase difference of the diffracted light cast intothe polarization axis 107 a inclined clockwise (x positive direction) issmaller than the phase difference of the diffracted light cast into thepolarization axis 107 b inclined counter-clockwise (x negativedirection), placing the quarter wave plate 104 c such that the directionof the slow axis of the quarter wave plate 104 c and the S-polarizationdirection (x direction) are generally parallel facilitates reduction ofstray diffracted light, thereby improving contrast.

Next, FIG. 9 illustrates a simplified diagram of a reflective liquidcrystal display device according to at least one exemplary embodiment,where the optical axis direction of the quarter wave plate 104 c hasbeen rotated 90° within the xy plane with respect to the positioningthereof shown in FIG. 1.

Reference numeral 104 a denotes the slow axis, and 104 b the fast axis.FIG. 10 illustrates the amount of stray light with respect to thedifference between the phase difference of the x negative directiondiffracted light and the phase difference of the x positive directiondiffracted light.

The sum of stray diffracted light in FIG. 10 is the minimal valueobtained by arbitrarily rotating the optical axis (slow axis) of thequarter wave plate 104 c within the xy plane. FIG. 11 illustrates theoptical axis rotation angle of the quarter wave plate 104 c where thesum of stray diffracted light is minimal.

Referring to FIG. 10, in the event that the x negative directiondiffracted light phase difference minus the x positive directiondiffracted light phase difference is zero or smaller, i.e., in the eventthat the phase difference of the diffracted light cast into thepolarization axis 107 a inclined clockwise (diffracted light proceedingin the x positive direction) is greater than the phase difference of thediffracted light cast into the polarization axis 107 b inclinedcounter-clockwise (diffracted light proceeding in the x negativedirection), the amount of stray diffracted light is small.

The phase difference of the diffracted light cast into the polarizationaxis 107 a inclined clockwise (x positive direction) is greater than thephase difference of the diffracted light cast into the polarization axis107 b inclined counter-clockwise (x negative direction). Placing thequarter wave plate 104 c such that the direction of the fast axis of thequarter wave plate 104 c and the S-polarization direction (x direction)are generally parallel, facilitates reduction of stray diffracted light,thereby improving contrast.

Now, the polarization state at each optical device in the optical systemillustrated in FIG. 1, from the point of the incident light 101 areflecting off of the polarization beam splitter 102 a to the point ofreturning to the polarization beam splitter 102 a will be described.Each polarization state is illustrated as viewed from the reflectiveliquid crystal display device 105 a side.

Let us consider a beam of incident light 101 a reflecting off of thepolarization split film 103 a with a polarization axis in theS-polarization direction (x direction). The direction of travel of thereflected beam is the z axial direction. FIG. 43 illustrates thepolarization state of a beam reflected off of the polarization splitfilm 103 a. In the diagram, x represents the x-axial direction and y they-axial direction, indicating that the beam is linear polarized lighthaving a polarization axis oscillating in the S-polarization direction(x-axial direction).

Further, the polarization state upon passing through the quarter waveplate 104 c is illustrated in FIGS. 44A and 44B. In FIGS. 44A and 44B,θ=0 represents a state where the respective slow axis and the fast axisof the quarter wave plate 104 c are parallel to the x direction, with apolarization state where rotation by one degree in the clockwisedirection as viewed from the reflective liquid crystal display device105 a is represented by θ=+1°, and rotation by one degree in thecounter-clockwise direction as viewed from the reflective liquid crystaldisplay device 105 a is represented by θ=−1°.

In either case of the slow axis reference (FIG. 44A) and the fast axisreference (FIG. 44B), the major axis is in the axis rotation direction,and phase difference twice the axis rotational angle is given. Further,the symbol is reversed for the phase difference between the slow axisreference and the fast axis reference.

The beam with the polarization state shown in FIGS. 44A and 44B is castinto the reflective liquid crystal display device 105 a. First, let usconsider a case where no phase difference is given at the reflectiveliquid crystal display device 105 a (phase difference of 0°). Thepolarization state of the beam shown in FIGS. 44 a and 44B is maintainedwhen reflecting, and the beam is input to the quarter wave plate 104 cagain. FIGS. 45A and 45B illustrate the respective polarization statesupon being transmitted through the quarter wave plate 104 c again. Ineither case of the slow axis reference (FIG. 45A) and the fast axisreference (FIG. 45B), a further 1° rotation is given in the optical axis(slow axis and fast axis) rotation direction of the quarter wave plate104, and the phase difference is 0°, i.e., linear polarized light. Thus,in the event that no phase difference is given at the reflective liquidcrystal display device 105 a, the beam is input to the polarizationsplit film 103 a in the polarization state shown in FIGS. 45A and 45B.

Also, in a case where +4° phase difference is given by the reflectiveliquid crystal display device 105 a, +4° is added to each phasedifference of the beam being cast into the reflective liquid crystaldisplay device 105 a shown in FIGS. 44A and 44B (FIGS. 46A and 46B).With respective polarization states, the major axis of the ellipticpolarized light does not change in comparison with the polarizationstate in FIGS. 44A and 44B; only the phase difference is added. FIGS.47A and 47B illustrate the respective polarization states upon beingtransmitted through the quarter wave plate 104 c again. Upon thepositive phase difference light passing through the quarter wave plate104 c based on the slow axis reference, the polarization axis rotates inthe counter-clockwise direction by an angle corresponding to half of thephase difference of the incident light, so the phase difference is 0°,i.e., linear polarized light. On the other hand, upon the positive phasedifference light passing through the quarter wave plate 104 c based onthe fast axis reference, the polarization axis rotates in the clockwisedirection by an angle corresponding to half of the phase difference ofthe incident light, so the phase difference is 0°, i.e., linearpolarized light. Accordingly, in the case of the slow axis reference asshown in FIG. 47A, the polarization axis of the beam being transmittedthrough the quarter wave plate 104 c rotates in the counter-clockwisedirection, while in the case of the fast axis reference as shown in FIG.47B, the polarization axis of the beam being transmitted through thequarter wave plate 104 c rotates in the clockwise direction. Thus, in acase that a phase difference of +4° is given at the reflective liquidcrystal display device 105 a, the beam is cast into the polarizationsplit film 103 a in the polarization state shown in FIGS. 47A and 47B.

Further, in a case where +8° phase difference is given by the reflectiveliquid crystal display device 105 a, +8° is added to each phasedifference of the beam being cast into the reflective liquid crystaldisplay device 105 a shown in FIGS. 44A and 44B. FIGS. 48A and 48B showthe respective polarization states upon being transmitted through thequarter wave plate 104 c again. Upon the positive phase difference lightpassing through the quarter wave plate 104 c based on the slow axisreference, the polarization axis rotates in the counter-clockwisedirection by 2° more with respect to the polarization axis directionshown in FIG. 47A, and on the other hand, upon the positive phasedifference light passing through the quarter wave plate 104 c based onthe fast axis reference, the polarization axis rotates in the clockwisedirection by 2° more with respect to the polarization axis directionshown in FIG. 47B. Thus, in a case that a phase difference of +8° isgiven at the reflective liquid crystal display device 105 a, the beam iscast into the polarization split film 103 a in the polarization stateshown in FIGS. 48A and 48B.

Thus, the polarization state of the beam being input to the polarizationsplit film 103 a is compared for the cases of 0°, +4°, and +8° in phasedifference for the diffracted light generated by the reflective liquidcrystal display device 105 a when displaying black. In at least oneexemplary embodiment, the diffracted light is generated in the x-axialpositive direction and the x-axial negative direction, cast into thepolarization axis inclinations 107 a and 107 b, and that thepolarization axis inclinations are each ±2° with respect to the x axialdirection.

In the case of slow axis reference (disposed near the x-axial direction;see FIGS. 45A, 47A, 48A) upon the phase difference of the diffractedlight generated at the reflective liquid crystal display device 105 aincreasing, the inclination direction of the polarization axis can beinclined in the counter-clockwise direction. In the event that theinclination of the polarization split film 103 a where diffracted lightwith great phase difference proceeds rotates in the counter-clockwisedirection, and the inclination of the polarization split film 103 awhere diffracted light with small phase difference proceeds rotates inthe clockwise direction, placing the slow axis of the quarter wave plate104 c near the S-polarization direction (x direction) facilitates theamount of stray light guided from the polarization beam splitter 102 ato the projection lens system (not shown) to be reduced, due to thepolarization axis direction of the diffracted light being inclinedtoward the polarization axis direction of the polarization split film103 a. Also, in the event of diffracted light with a small phasedifference of 0° being cast into the polarization axis inclination 107 arotated 2° in the clockwise direction, and diffracted light with a greatphase difference of +8° being cast into the polarization axisinclination 107 b rotated 2° in the counter-clockwise direction, thepolarization axis direction of each refracted light matches thepolarization axis inclination direction (±2°) of the respectivepolarization split films 103 a with the slow axis rotation angle of thequarter wave plate 104 c at +1°, according to FIGS. 45A and 48A, so thediffracted light is analyzed and there is little stray light.

On the other hand, in the case of slow axis reference (disposed near thex-axial direction; see FIGS. 45B, 47B, 48B) upon increasing the phasedifference of the diffracted light generated at the reflective liquidcrystal display device 105 a, the inclination direction of thepolarization axis can be inclined in the clockwise direction. In theevent that the inclination of the polarization split film 103 a wherediffracted light with great phase difference proceeds rotates in thecounter-clockwise direction, and the inclination of the polarizationsplit film 103 a where diffracted light with great phase differenceproceeds rotates in the clockwise direction, placing the fast axis ofthe quarter wave plate 104 c near the S-polarization direction (xdirection) facilitating the amount of stray light guided from thepolarization beam splitter 102 a to the projection lens system (notshown) to be reduced, due to the polarization axis direction of thediffracted light being inclined toward the polarization axis directionof the polarization split film 103 a. Also, in the event of diffractedlight with a small phase difference of +8° being cast into thepolarization axis inclination 107 a rotated 2° in the clockwisedirection, and diffracted light with a great phase difference of 0°being cast into the polarization axis inclination 107 b rotated 2° inthe counter-clockwise direction, the polarization axis direction of eachrefracted light matches the polarization axis inclination direction (±2°of the respective polarization split films 103 a with the slow axisrotation angle of the quarter wave plate 104 c at −1°, according toFIGS. 45A and 48A, so the diffracted light is analyzed and there islittle stray light.

FIG. 12 illustrates an overall drawing of a reflective liquid crystaldisplay apparatus which is the first exemplary embodiment. In thedrawing, reference numeral 1 denotes a light source (e.g., formed of ahigh-pressure mercury vapor lamp), 2 denotes a reflector for emittingthe light from the light source 1 in a predetermined direction, 3denotes an integrator formed of cylindrical lens arrays 3 a and 3 b(optical devices where multiple cylindrical lenses are arrayed; thecylindrical lenses can be fly-eye lenses) configured to form a lightingregion having a substantially uniform illumination intensity, 4 denotesa polarization conversion element including a polarization split film 4a and a reflecting film 4 c and a half wave plate 4 b (see enlargementin FIG. 12) configured to align unpolarized light in a predeterminedpolarization direction, 5 denotes a condenser lens for condensingillumination light, 6 denotes a mirror, 7 denotes a field lens forchanging illumination light into telecentric light, 8 denotes a dichroicmirror for transmitting light of the green wavelength band. In otherexemplary embodiments, the dichroic mirror can be designed for anon-green wavelength band. Reference numbers 9 a 1, 9 b 1, and 9 c 1 areeach polarization split films having properties for reflectingS-polarized light and transmitting P-polarized light, 9 a, 9 b, and 9 care each polarization beam splitters having the polarization split films9 a 1, 9 b 1, and 9 c 1, 10 a and 10 b are color selective wave plateseach for converting (rotating) the polarization direction of light ofpredetermined wavelength bands by 90°, 11 r, 11 g, and 11 b arereflective liquid crystal display devices for reflecting incidentillumination light while forming image light by modulating incidentillumination light according to image signals, 12 r, 12 g, and 12 b areeach quarter wave plates, 13 denotes a UV cut filter for cutting outlight of the ultraviolet wavelength band, and 14 denotes a projectionlens system.

Next, the optical effects of the above configuration will be described.The light emitted from the light source 1 is reflected off of thereflector 2, is transmitted through the UV cut filter 13 configured toreduce ultraviolet wavelength band light, and is condensed in thedirection of the cylindrical lens 3 a. This light flux is split intomultiple light fluxes by the cylindrical lens 3 a, and then superimposedupon the reflective liquid crystal display devices 11 r, 11 g, and 11 b,by the effects of the cylindrical lens 3 b, condenser lens 5, and filedlens 7, thereby forming illumination regions of substantially uniformillumination intensity on the reflective liquid crystal display devices11 r, 11 g, and 11 b. Also the multiple light fluxes which have beenemitted from the cylindrical lens 3 b are split into P-polarizationlight and S-polarization light at the polarization split film 4 a,corresponding to each of the light fluxes. The P-polarization light isconverted into a polarization component having the same direction as theS-polarization light by the half wave plate 4 c, and the S-polarizationlight is reflected by the reflecting film 4 b. The multiple light fluxesemitted form the cylindrical lens 3 b are emitted in the same directionas light having a predetermined polarization direction. The light whichhas been generally aligned to S-polarization light by the polarizationconversion element 4 is cast into the dichroic mirror 8 which transmitslight of the green wavelength band, and light of the red and bluewavelength bands is reflected. The light of the green wavelength bandwhich has been transmitted through the dichroic mirror 8 is cast intothe polarization beam splitter 9 a, reflected off of the polarizationsplit film 9 a 1, transmitted through the quarter wave plate 12 g, andcast into the reflective liquid crystal display device 11 g. On theother hand, of the light of the red and blue wavelength bands which hasbeen reflected off of the dichroic mirror 8, just the light of the bluewavelength band has the polarization direction thereof changed by 90° bythe first color selective wave plate 10 a, thereby becomingP-polarization light, and the light of the red wavelength band remainsS-polarization light and enters the polarization beam splitter 9 b.Further, the light of the blue wavelength band, which is P-polarizationlight, is transmitted through the polarization split film 9 b 1 of thepolarization beam splitter 9 b, and the light of the red wavelength bandwhich is S-polarization light is reflected. Thus, the light is splitinto red and blue wavelength bands of which the polarization directionis mutually substantially orthogonal. The light of the red wavelengthband which has been reflected off of the polarization beam splitter 9 bis transmitted through the quarter wave plate 12 r, and cast into thereflective liquid crystal display device 11 r, while the light of theblue wavelength band which has been transmitted through the polarizationbeam splitter 9 b is transmitted through the quarter wave plate 12 b,and cast into the reflective liquid crystal display device 11 b.

Further, the light of the green wavelength band which has been subjectedto 180° phase difference modulation and reflection by the reflectiveliquid crystal display device 11 g is transmitted through the quarterwave plate 12 g, and becomes P-polarization light that is transmittedthrough the polarization beam splitters 9 a and 9 c. Also, the light ofthe red wavelength band which has been subjected to 180° phasedifference modulation and reflection by the reflective liquid crystaldisplay device 11 r is transmitted through the quarter wave plate 12 r,and becomes P-polarization light that is transmitted through thepolarization beam splitter 9 b, and is cast into the second colorselective wave plate 12 b. Also, the light of the blue wavelength bandwhich has been subjected to 180° phase difference modulation andreflection by the reflective liquid crystal display device 11 b istransmitted through the quarter wave plate 12 b, becomes S-polarizationlight that is reflected off of the polarization beam splitter 9 b, andis cast into the second color selective wave plate 12 b. Of the light ofthe red and blue wavelength bands that has been cast into the secondcolor selective wave plate 10 b which converts the polarizationdirection of only the light of the red wavelength band by 90°, just thepolarization direction of the light of the red wavelength band ischanged by 90° by the second color selective wave plate 10 b and becomesS-polarization light. The light of the blue wavelength band is cast intothe polarization beam splitter 9 c as S-polarization light, and isreflected. The light of the entire RGB wavelength band is synthesized bythe polarization beam splitter 9 c, guided to the projection lens 14,and is projected on screen (not shown).

Now, FIG. 13 illustrates the optical path of the green light which hasbeen subjected to color separation by the dichroic mirror 8, using thepolarization beam splitter 9 a, the polarization split film 9 a 1, thequarter wave plate 12 g, and the reflective liquid crystal displaydevice 11 g. In the drawing, reference numeral 15 g denotes incidentlight which is light of the green band which has been subjected to colorseparation by the dichroic mirror 8 being cast into the polarizationbeam splitter 9 a. 16 a denotes incident beams from the X positivedirection within the xy plane, and 16 b denotes incident beams from thex negative direction within the xy plate. 17 a denotes the polarizationaxis of the incident light 16 a inclined by the polarization split film9 a 1, and 17 b denotes the polarization axis of the incident light 16 binclined by the polarization split film 9 a 1. The incident light axisof the polarization beam splitter 9 a is the y direction, the reflectionlight axis the z direction, and the direction substantiallyperpendicular to the xy plane the x direction. Generally, grazingincidence light to the polarization split film of a polarization beamsplitter exhibits geometric inclination of the polarization axis at thetime of reflecting or transmitting the polarization split film. With thepresent exemplary embodiment, as illustrated in FIG. 13, the incidentbeam 16 a from the x positive direction has the polarization axis 17 athereof inclined in the clockwise direction as viewed from the zpositive direction at the time of reflecting off of the polarizationsplit film 9 a 1, and the polarization axis 17 b of the incident beam 16b from the x negative direction can be inclined in the counter-clockwisedirection as viewed from the z positive direction at the time ofreflecting off of the polarization split film 9 a 1.

Further, the incident beam 16 a is transmitted through the quarter waveplate 12 g, reflected off of the reflective liquid crystal displaydevice 11 g, transmitted through the quarter wave plate 12 g again, andcast into the polarization split film 9 a 1 of the polarization beamsplitter 9 a. The beam 16 a, which has been reflected off of thereflective liquid crystal display device 11 g, proceeds in the xnegative direction, and is cast into the polarization split film 9 a 1having a polarization axis 17 b inclination which is linearlysymmetrical on the x axis with respect to the polarization axis 17 a.Also, the incident beam 16 b is transmitted through the quarter waveplate 12 g, reflected off of the reflective liquid crystal displaydevice 11 g, is transmitted through the quarter wave plate 12 g again,and is cast into the polarization split film 9 a 1 of the polarizationbeam splitter 9 a. The beam 16 b which has been reflected off of thereflective liquid crystal display device 11 g proceeds in the x positivedirection, and is cast into the polarization split film 9 a 1 having apolarization axis 17 a inclination which is linearly symmetrical on thex axis with respect to the polarization axis 17 b.

Further, the incident beams 16 a and 16 b, corresponding to thedirections of the polarization axis 17 b and polarization axis 17 a ofthe polarization split film 9 a 1, are analyzed and transmitted.

The reflective liquid crystal display device 11 g according to thepresent exemplary embodiment is of a vertical orientation normally-blackdisplay mode, where the display is black when the effective voltage ofthe liquid crystal is around 0 Vrms, and displays white when voltage isapplied. The structure thereof is illustrated in FIG. 14. In thedrawing, reference numeral 201 denotes an active matrix substrate, 202denotes an opposing glass substrate, 203 denotes a liquid crystal layer,204 denotes a Si substrate, 205 denotes an active device layer, 206denotes a shielding layer, 207 denotes reflecting pixel electrodes, 208and 209 denote orientation films, 210 denotes a transparent electrode,and 211 denotes a glass substrate. The active matrix substrate 201 ismade up of the active device layer 205 which drives the pixels on the Sisubstrate 204 to reflect light, the reflecting pixel electrodes 207, theorientation film 208, and the shielding layer 206 for shielding straylight, and the opposing glass substrate 202 is made up of thetransparent electrode 210 and the orientation film 209 formed on theglass substrate 211, with the liquid crystal layer 203 being sandwichedin between the active matrix substrate 201 and the opposing glasssubstrate 202. Also, the pixel shape of the reflecting pixel electrodes207 is a 10 μm by 10 μm square, arrayed vertically and horizontally inmatrix fashion. Note that the reflecting pixel electrodes 207 of thereflective liquid crystal display device 11 g shown in FIG. 14 arearrayed in matrix fashion in the x direction and the y direction.

Generally, the closer the liquid crystal orientation angle in a blackdisplay state is substantially perpendicular with respect to thesubstrate, a wider viewing angle can be realized, but in at least oneexemplary embodiment, the direction of rotation of the liquid crystalmolecules is restricted at the time of performing gradation display orwhite display by the voltage applied, so a liquid crystal molecule tiltangle can be used.

FIG. 15 illustrates the phase difference incident angle properties ofthe reflective liquid crystal display device 11 g for black display in acase where the direction of tilt of the reflective liquid crystaldisplay device is an inclination around 45° with respect to thepolarization plane (xz plane) of S-polarization with respect to thepolarization split plane 9 a 1 of the polarization beam splitter 9 a,for both the glass substrate 202 side and the Si substrate 204 side, andfurther where the tilt angle is an angle inclined several degrees from90°, which is the substantially perpendicular direction to thesubstrate. In FIG. 15, the angular radial lines correspond to incidentlight directions. The incident light directions to the reflective liquidcrystal display device 11 g in FIG. 15 are the y axis negative directionrelated to the orientation angle of 0°, the x axis positive direction isrelated to the orientation angle of 90°, the y axis positive directionis related to the orientation angle of 180°, and the x axis negativedirection is related to the orientation angle of 270°, respectively.Also, generally, in the case that the tilt angle is 90°, the phasedifference is great in the direction of the orientation angles 45°,135°, 225°, and 315°, and the phase difference is small in the directionof the orientation angles 0°, 90°, 180°, and 270°. While this exhibits across-shaped four-way symmetrical phase counter shape, inclining thetile angle several degrees from 90° yields non-symmetrical properties,as illustrated in FIG. 1. The phase difference is great in the directionof the orientation angles 45° and 225°, and the phase difference issmall in the direction of the orientation angles 135° and 315°.

Also, FIG. 16 illustrates a phase difference pattern of diffracted lightgenerated upon substantially perpendicular input of a beam to thereflective liquid crystal display device 11 g while displaying black.The reflecting electrodes 207 of the reflective liquid crystal displaydevice 11 g shown in FIG. 14 are arrayed in matrix fashion in the xdirection and the y direction, so diffracted (interference) light isgenerated in the x direction and the y direction. In this particularexample, the diffraction angle is 3.5°, while taking into considerationan output angle of 17.5° (5th order light) projected from the projectionlight system 14. The orientation angle 0° direction represents thediffracted light generated in the y axis negative direction, theorientation angle 90° direction represents the diffracted lightgenerated in the x axis positive direction, the orientation angle 180°direction represents the diffracted light generated in the y axispositive direction, and the orientation angle 270° direction representsthe diffracted light generated in the x axis negative direction.

The 0th order light and diffracted light reflected off of the reflectiveliquid crystal display device 11 g are transmitted through the quarterwave plate 12 b, and are cast into the polarization film 9 a 1 of thepolarization beam splitter 9 a, respectively. The polarization axisinclination angle of the polarization split film 9 a 1 geometricallychanges according to the incident angle, so the 0th order light and thediffracted light each are subjected to analyzing of the polarizationcomponent in the direction of the polarization axis inclination anglecorresponding to the angle of incidence to the polarization split film 9a 1, and the polarization component substantially perpendicular to thepolarization axis inclination direction is transmitted and becomes straylight.

FIG. 17 illustrates the inclination of the polarization axiscorresponding to the incident angle, which is generated at thepolarization film 9 a 1 of the polarization beam splitter 9 a. Thedefinition of the orientation angles in FIG. 17 is the same as with FIG.16, with the orientation angle 0° direction representing the diffractedlight generated in the y axis negative direction, the orientation angle90° direction representing the diffracted light generated in the x axispositive direction, the orientation angle 180° direction representingthe diffracted light generated in the y axis positive direction, and theorientation angle 270° direction representing the diffracted lightgenerated in the x axis negative direction, as viewed from the axialdirection of incidence to the polarization split film 9 a 1 from thereflective liquid crystal display device 11 g. Further, clockwiserotation of the polarization axis inclination as viewed from the z axispositive direction is positive, and counter-clockwise rotation isnegative.

According to FIG. 17, the direction of polarization axis inclination ofthe polarization beam splitter 9 a is a direction parallel to thepolarization plane of the S-polarization direction (x direction),without inclination of the polarization axis with respect to incidentbeams from within the yz plane at orientation angle 0° (360° and 180°).On the other hand, the closer the orientation angle approaches 90°(270°) from 0° (180°), the greater the inclination of the polarizationaxis becomes, and the greater the incident tilt angle is the greater thepolarization axis can be inclined. Also, the polarization axisinclination is clockwise for beams entering in the x positive direction,and the polarization axis inclination is counter-clockwise for beamsentering in the x negative direction.

Now, FIGS. 18A and 18B illustrate the 0th order stray light of thereflective liquid crystal display device 11 g when displaying black. Thestray light calculation method will be described with reference to theoptical system shown in FIG. 13. At the time of the incident light 15 greflecting off of the polarization split film 9 a 1, the polarizationsplit film 9 a 1 serves as a polarizer, and the light is cast into thequarter wave plate 12 g with a polarization axis inclinationcorresponding to each incident angle shown in FIG. 17. The light fluxwhich has transmitted through the quarter wave plate 12 g has phasedifference corresponding to each incident angle shown in FIG. 15, sobeams of each incident angle are subjected to phase effects, reflectedoff of the reflective liquid crystal display device 11 g, transmittedthrough the quarter wave plate 12 g again, and cast into thepolarization split film 9 a 1. The polarization split film 9 a 1 servesas an analyzer, having polarization axis inclination corresponding toeach inclination angle shown in FIG. 17, where the polarization axisinclination direction is the analyzing axis direction, and polarizationcomponents other than the analyzing axis direction become stray light.Note that the phase difference of the quarter wave plate is calculatedas 90°.

FIG. 18A illustrates the ratio of stray light intensity with respect toincident light intensity as contrast, in a case of rotation within thexy plane with the direction where the direction of the fast axis and thedirection of the x axis match as a reference (where the quarter phasedifference axis rotation angle=0°), and FIG. 18B in a case of rotationwithin the xy plane with the direction where the direction of the slowaxis and the direction of the x axis match as a reference (where thequarter phase difference axis rotation angle=0°). The clockwisedirection of the rotation angle of the quarter wave plate as viewed fromthe z positive direction is the positive direction, and thecounter-clockwise direction is the negative direction. The outermostangle of the incident illumination light here to the reflective liquidcrystal display device 11 g is 12°.

As can be seen from FIGS. 18A and 18B, in the event that the fast axisis near the S-polarization direction, the contrast is maximum at 2968when rotated −0.9° in the negative direction, and in the event that theslow axis is near the S-polarization direction, the contrast is maximumat 2969 when rotated +0.9° in the positive direction. As for 0th orderlight, the contrast, i.e., stray light is equal, and is not dependent onthe disposing direction (fast axis and slow axis direction) of theoptical axis of the quarter wave plate 12 g.

Next, stray light of the diffracted light will be calculated. Theincident angle to the polarization split film 9 a 1 of the polarizationbeam splitter 9 a differs for diffracted light of differing orders, thusone can take into consideration the polarization axis inclination 17 a(17 b) according to the order of the diffracted light.

FIG. 19 shows the diffraction angle of diffracted light of each orderand the polarization axis inclination of the polarization beam splitter9 a. Here, the polarization axis inclination angle of the polarizationbeam splitter 9 a is generated only for the diffracted light of theorientation angle 90° (x positive direction) and orientation angle 270°(x negative direction), and polarized light components of eachpolarization axis inclination angle direction are analyzed.

FIGS. 20A and 20B illustrate the amount of stray light of diffractedlight in a case of the optical axis (fast axis and slow axis) of thequarter wave plate 12 g being rotated within the xy plane. Here, the sumof stray light of the diffracted light of the 1st order through the 5thorder is shown as the sum of diffraction stray light regarding eachorientation angle (0°, 90°, 180°, and 270°, where the orientation angle0° is the y axis negative direction, the orientation angle 90° is the xaxis positive direction, the orientation angle 180° is the y axispositive direction, and the orientation angle 270° is the x axisnegative direction). Also here, each diffracted light intensitygenerated from the reflective liquid crystal display device 11 g isrepresented as 1.

FIG. 20A illustrates a case where the fast axis is set with the xdirection as a reference (i.e., the state where the fast axis faces theX positive direction is 0° in FIG. 20A), and FIG. 20B illustrates a casewhere the slow axis is set with the x direction as a reference (i.e.,the state where the slow axis faces the X positive direction is 0° inFIG. 20B). It can be seen from FIG. 20A that the minimum value of thesum of all diffracted stray light is 0.225 with the fast axis inclinedby −1.5°, and from FIG. 20B that the minimum value of the sum of alldiffracted stray light is 0.045 with the slow axis inclined by +1.5°.Thus, with the present exemplary embodiment, the amount of diffractionstray light can be reduced to around one fifth, and contrast can beimproved, by based on the slow axis on the x direction, and furtherinclining by +1.5°.

Also, the sum of diffracted stray light in the orientation angle 0° and180° which is cast into the direction where there is no polarizationaxis inclination due to the polarization split film 9 a 1 of thepolarization beam splitter 9 a is 0.030 (FIG. 20A) when the fast axiscan be inclined −1.5° from the x axis direction, and is 0.030 (FIG. 20B)when the slow axis can be inclined +1.5° from the x axis direction,meaning that the contrast is not dependent on the optical axispositioning direction of the quarter wave plate 12 g (the direction ofthe fast axis or slow axis).

On the other hand, the sum of diffracted stray light in the orientationangle 90° and 270° which is cast into the direction where there ispolarization axis inclination due to the polarization split film 9 a 1of the polarization beam splitter 9 a is 0.195 (FIG. 20A) when the fastaxis can be inclined −1.5° from the x axis direction, and is 0.145 (FIG.20B) when the slow axis can be inclined +1.5° from the x axis direction,meaning that the contrast is dependent on the optical axis positioningdirection of the quarter wave plate 12 g (the direction of the fast axisor slow axis).

According to FIGS. 18A, 18B, 20A, and 20B, performance of contrast(amount of stray light) with regard to the optical axis placementdirection of the quarter wave plate 12 g depends on the phase differenceof the diffracted light generated in the S-polarization direction (theorientation angle 90° and orientation angle 270° directions) by thereflective liquid crystal display device 11 g when displaying black, soan image display device with high contrast can be obtained by placingthe quarter wave plate 12 g such that the direction of the slow axis ofthe quarter wave plate 12 g and the S polarization direction (xdirection) are generally parallel in a case where the phase differenceof the diffracted light cast into the polarization axis direction 107 ainclined clockwise with respect to the S-polarization direction (xdirection) as viewed from the reflective liquid crystal display device11 g side is smaller than the phase difference of the diffracted lightcast into the polarization axis direction 107 b inclinedcounter-clockwise.

Also, keeping the generally-parallel angle between the slow axisdirection of the quarter wave plate 12 g and the S-polarizationdirection within 5° yields images with high contrast, and keeping thiswithin 3° yields images with even higher contrast.

Next, FIG. 21 illustrates the optical path of the red light which hasbeen subjected to color separation by the dichroic mirror 8 in detail,using the polarization beam splitter 9 b, the polarization split film 9b 1, the quarter wave plate 12 r, and the reflective liquid crystaldisplay device 11 r. In the drawing, reference numeral 15 rb denotesincident light which is light of the red band which has been subjectedto color separation by the dichroic mirror 8 being cast into thepolarization beam splitter 9 b, 16 a denotes incident beams from the Xpositive direction within the xy plane, 16 b denotes incident beams fromthe x negative direction within the xy plate, 17 b denotes thepolarization axis of the incident light 16 a inclined by thepolarization split film 9 b 1, and 17 a denotes the polarization axis ofthe incident light 16 b inclined by the polarization split film 9 b 1,with the incident light axis of the polarization beam splitter 9 b beingthe y direction, the reflection light axis the z direction, and thedirection substantially perpendicular to the xy plane the x direction.

As shown in FIG. 21, the incident beam 16 a from the x positivedirection has the polarization axis 17 b thereof inclined in thecounter-clockwise direction as viewed from the z positive direction atthe time of reflecting off of the polarization split film 9 b 1, and thepolarization axis 17 a of the incident beam 16 b from the x negativedirection can be inclined in the clockwise direction as viewed from thez negative direction at the time of reflecting off of the polarizationsplit film 9 b 1. The configuration is such that the polarization axisinclination generated at the polarization split film 9 b 1 of thepolarization beam splitter 9 b is inverted within the yz plane whencompared within incident beams 16 a and 16 b of the green optical pathshown in FIG. 13.

Further, the incident beam 16 a is transmitted through the quarter waveplate 12 r, reflected off of the reflective liquid crystal displaydevice 11 r, is transmitted through the quarter wave plate 12 r again,and is cast into the polarization split film 9 b 1 of the polarizationbeam splitter 9 b. The beam 16 a which has been reflected off of thereflective liquid crystal display device 11 r proceeds in the x negativedirection, and is cast into the polarization split film 9 b 1 having apolarization axis 17 a inclination which is linearly symmetrical on thex axis with respect to the polarization axis 17 b. Also, the incidentbeam 16 b is transmitted through the quarter wave plate 12 r, reflectedoff of the reflective liquid crystal display device 11 r, is transmittedthrough the quarter wave plate 12 r again, and is cast into thepolarization split film 9 b 1 of the polarization beam splitter 9 b. Thebeam 16 b, which has been reflected off of the reflective liquid crystaldisplay device 11 r, proceeds in the x positive direction, and is castinto the polarization split film 9 b 1 having a polarization axis 17 binclination which is linearly symmetrical on the x axis with respect tothe polarization axis 17 a.

Further, the incident beams 16 a and 16 b are analyzed and transmittedcorresponding to the direction of the polarization axis 17 b andpolarization axis 17 a of the polarization split film 9 b 1,respectively.

The reflective liquid crystal display device 11 r of the red light pathhas the same properties of the reflective liquid crystal display device11 g of the green light path, and is rotated 180° with respect to thereflective liquid crystal display device 11 g of the green light pathwithin the reflective liquid crystal display device face (the xy planein FIGS. 13 and 21).

FIG. 22 illustrates the phase difference incident angle properties ofthe reflective liquid crystal display device 11 r for black display. Theincident light directions to the reflective liquid crystal displaydevice 11 r in FIG. 22 are defined as the y axis negative direction forthe orientation angle of 0°, the x axis positive direction for theorientation angle of 90°, the y axis positive direction for theorientation angle of 180°, and the x axis negative direction for theorientation angle of 270°, respectively. Here, with Δn as the refractiveindex difference of ordinary rays and extraordinary rays with respect tothe thickness of the liquid crystal layer, d as the liquid crystal layerthickens, and λ as the incident wavelength, the phase difference whendisplaying black obtained by Δnd/λ shows that the λ of the black displayphase difference of red band input shown in FIG. 22 is greater than thatof the black display phase difference of green band input shown in FIG.15, meaning that the phase difference is small.

Also, FIG. 23 illustrates a phase difference pattern of diffracted lightgenerated at the reflective liquid crystal display device 11 r whiledisplaying black. The reflecting pixel electrodes 207 of the reflectiveliquid crystal display device 11 r shown in FIG. 21 are arrayed inmatrix fashion in the x direction and the y direction, so diffracted(interference) light is primarily generated in the x direction and the ydirection. The diffraction angle is 4.0°, and an output angle of 20°(5th order light) projected from the projection light system 14 has beentaken into consideration. Also, the orientation angle 0° directionrepresents the diffracted light generated in the y axis negativedirection, the orientation angle 90° direction represents the diffractedlight generated in the x axis positive direction, the orientation angle180° direction represents the diffracted light generated in the y axispositive direction, and the orientation angle 270° direction representsthe diffracted light generated in the x axis negative direction. Now,the reflective liquid crystal display device 11 r in the red light pathis rotated by 180° within the reflective liquid crystal display deviceplane (the xy plane in FIGS. 13 and 21) with respect to the reflectiveliquid crystal display device 11 g in the green light path, so the phasedifference pattern of diffracted light is rotated 180° as compared tothat in FIG. 16.

FIG. 24 illustrates the inclination of the polarization axiscorresponding to the incident angle, which is generated at thepolarization film 9 b 1 of the polarization beam splitter 9 b. Thedefinition of the orientation angles in FIG. 24 is the same as with FIG.22, with the orientation angle 0° direction representing the diffractedlight generated in the y axis negative direction with respect to thepolarization split film 9 b 1, the orientation angle 90° directionrepresenting the diffracted light generated in the x axis positivedirection, the orientation angle 180° direction representing thediffracted light generated in the y axis positive direction, and theorientation angle 270° direction representing the diffracted lightgenerated in the x axis negative direction, as viewed from the axialdirection of incidence to the polarization split film 9 b 1 from thereflective liquid crystal display device 11 r. Further, clockwiserotation of the polarization axis inclination as viewed from the z axispositive direction is positive, and counter-clockwise rotation isnegative.

Note that the polarization axis inclination direction of the red lightpath in FIG. 24 is inverted in the yz plane with respect to thepolarization axis inclination of the green light path shown in FIG. 17.

Now, FIGS. 25A and 25B illustrate the amount of the 0th order straylight of the reflective liquid crystal display device 11 r whendisplaying black. The phase difference of 0th order light is as shown inFIG. 22. FIG. 25A illustrates the ratio of stray light intensity withrespect to incident light intensity as contrast, in a case of rotationwithin the xy plane with the direction where the direction of the fastaxis and the direction of the x axis match as a reference (where thequarter phase difference axis rotation angle=0°), and FIG. 25B in a caseof rotation within the xy plane with the direction where the directionof the slow axis and the direction of the x axis match as a reference(where the quarter phase difference axis rotation angle=0°). Theclockwise direction of the rotation angle of the quarter wave plate asviewed from the z positive direction is the positive direction, and thecounter-clockwise direction is the negative direction. The outermostangle of the incident illumination light here to the reflective liquidcrystal display device 11 r is 12°.

As can be seen from FIGS. 25A and 25B, with the fast axis as thereference, the contrast is maximum at 3328 when rotated −0.7° in thenegative direction, and with the slow axis as the reference, thecontrast is maximum at 3330 when rotated +0.7° in the positivedirection. As for 0th order light, the contrast, i.e., stray light, isequal, and is not dependent on the disposing direction (fast axis andslow axis direction) of the optical axis of the quarter wave plate 12 r.

Next, stray light of the diffracted light will be calculated. FIG. 26shows the diffraction angle of diffracted light of each order and thepolarization axis inclination angle of the polarization beam splitter 9b. Here, the polarization axis inclination angle of the polarizationbeam splitter 9 a is generated only for the diffracted light of theorientation angle 90° (x positive direction) and orientation angle 270°(x negative direction), and analyzing and transmission (stray light)occurs according to each polarization axis inclination angle.

FIGS. 27A and 27B illustrate the amount of stray light of diffractedlight in a case of the optical axis (fast axis and slow axis) of thequarter wave plate 12 r being rotated within the xy plane. Here, the sumof stray light of the diffracted light of the 1st order through the 5thorder is shown as the sum of diffraction stray light regarding eachorientation angle (0°, 90°, 180°, and 270°), and each diffracted lightintensity generated from the reflective liquid crystal display device 11r is represented as 1.

FIG. 27A illustrates a case where the fast axis is set with the xdirection as a reference, and FIG. 27B illustrates a case where the slowaxis is set with the x direction as a reference. It can be seen fromFIG. 27A that the minimum value of the sum of all diffracted stray lightis 0.210 with the fast axis inclined by −1.5°, and from FIG. 27B thatthe minimum value of the sum of all diffracted stray light is 0.043 withthe slow axis inclined by +1.5°. Thus, with the present exemplaryembodiment, the amount of diffraction stray light can be reduced toaround one fifth, and contrast can be improved, by placing the slow axisbased on the x direction, and further inclining by +1.5°.

Also, the sum of diffracted stray light in the orientation angle 0° and180° which is cast into the direction where there is no polarizationaxis inclination due to the polarization split film 9 b 1 of thepolarization beam splitter 9 b is 0.026 (FIG. 27A) when the fast axiscan be inclined −1.5° from the x axis direction, and is 0.026 (FIG. 27B)when the slow axis can be inclined +1.5° from the x axis direction,meaning that the contrast is not dependent on the optical axispositioning direction of the quarter wave plate 12 r (the direction ofthe fast axis or slow axis).

On the other hand, the sum of diffracted stray light in the orientationangle 90° and 270° which is cast into the direction where there ispolarization axis inclination due to the polarization split film 9 b 1of the polarization beam splitter 9 b is 0.184 (FIG. 27A) when the fastaxis can be inclined −1.5° from the x axis direction, and is 0.017 (FIG.27B) when the slow axis can be inclined +1.5° from the x axis direction,meaning that the contrast is dependent on the optical axis positioningdirection of the quarter wave plate 12 r (the direction of the fast axisor slow axis).

Keeping the generally-parallel angle between the slow axis direction ofthe quarter wave plate 12 r and the S-polarization direction within 5°yields images with high contrast, and keeping this within 3° yieldsimages with even higher contrast.

Next, FIG. 28 illustrates the optical path of the blue light which hasbeen subjected to color separation by the dichroic mirror 8 in detail,using the polarization beam splitter 9 b, the polarization split film 9b 1, the quarter wave plate 12 b, and the reflective liquid crystaldisplay device 11 b. In the drawing, reference numeral 15 rb denotesincident light which is light of the blue band which has been subjectedto color separation by the dichroic mirror 8 being cast into thepolarization beam splitter 9 b, 16 a denotes incident beams from the Xpositive direction within the xy plane, 16 b denotes incident beams fromthe x negative direction within the xy plate, 18 a denotes thepolarization axis of the incident light 16 a inclined by thepolarization split film 9 b 1, and 18 b denotes the polarization axis ofthe incident light 16 b inclined by the polarization split film 9 b 1,with the incident light axis of the polarization beam splitter 9 b beingthe y direction, the reflection light axis the z direction, and thedirection substantially perpendicular to the xy plane the x direction.

As shown in FIG. 28, the incident beam 16 a from the x positivedirection has the polarization axis 18 a thereof inclined in thecounter-clockwise direction as viewed from the z positive direction atthe time of transmitting the polarization split film 9 b 1, and thepolarization axis 18 b of the incident beam 16 b from the x negativedirection can be inclined in the clockwise direction as viewed from thez negative direction at the time of transmitting the polarization splitfilm 9 b 1.

Further, the incident beam 16 a is transmitted through the quarter waveplate 12 b, reflected off of the reflective liquid crystal displaydevice 11 b, is transmitted through the quarter wave plate 12 b again,and is cast into the polarization split film 9 b 1 of the polarizationbeam splitter 9 b. The beam 16 a which has been reflected off of thereflective liquid crystal display device 11 b proceeds in the x negativedirection, and is cast into the polarization split film 9 b 1 having apolarization axis 18 b inclination which is linearly symmetrical on thex axis with respect to the polarization axis 18 a. Also, the incidentbeam 16 b is transmitted through the quarter wave plate 12 b, reflectedoff of the reflective liquid crystal display device 11 b, is transmittedthrough the quarter wave plate 12 b again, and is cast into thepolarization split film 9 b 1 of the polarization beam splitter 9 b. Thebeam 16 b which has been reflected off of the reflective liquid crystaldisplay device 11 b proceeds in the x positive direction, and is castinto the polarization split film 9 b 1 having a polarization axis 18 ainclination which is linearly symmetrical on the x axis with respect tothe polarization axis 18 b.

Further, the incident beams 16 a and 16 b are analyzed and transmittedcorresponding to the direction of the polarization axis 18 b andpolarization axis 18 a of the polarization split film 9 b 1,respectively.

The reflective liquid crystal display device 11 b of the blue light pathhas the same properties of the reflective liquid crystal display device11 g of the green light path.

FIG. 29 illustrates the phase difference incident angle properties ofthe reflective liquid crystal display device 11 b for black display. Theincident light directions to the reflective liquid crystal displaydevice 11 b in FIG. 29 are defined as the y axis negative direction forthe orientation angle of 0°, the x axis positive direction for theorientation angle of 90°, the y axis positive direction for theorientation angle of 180°, and the x axis negative direction for theorientation angle of 270°, respectively. Here, with Δn as the refractiveindex difference of ordinary rays and extraordinary rays with respect tothe thickness of the liquid crystal layer, d as the liquid crystal layerthickens, and λ as the incident wavelength, the phase difference whendisplaying black obtained by Δnd/λ shows that the λ of the black displayphase difference of blue band input shown in FIG. 29 is smaller thanthat of the black display phase difference of green band input shown inFIG. 15, meaning that the phase difference is great.

Also, FIG. 30 illustrates a phase difference pattern of diffracted lightgenerated at the reflective liquid crystal display device 11 b whiledisplaying black. The reflecting pixel electrodes 207 of the reflectiveliquid crystal display device 11 b shown in FIG. 29 are arrayed inmatrix fashion in the x direction and the y direction, so diffracted(interference) light is primarily generated in the x direction and the ydirection. The diffraction angle is 3.0°, and an output angle of 15°(5th order light) projected from the projection light system 14 has beentaken into consideration. Also, the orientation angle 0° directionrepresents the diffracted light generated in the y axis negativedirection, the orientation angle 90° direction represents the diffractedlight generated in the x axis positive direction, the orientation angle180° direction represents the diffracted light generated in the y axispositive direction, and the orientation angle 270° direction representsthe diffracted light generated in the x axis negative direction.

The inclination of the polarization axis generated at the polarizationsplit film 9 b 1 of the polarization beam splitter 9 b is the same asthat of the green light path, shown in FIG. 17.

Now, FIGS. 31A and 31B illustrate the 0th order stray light of thereflective liquid crystal display device 11 b when displaying black. Thephase difference of 0th order light is as shown in FIG. 29. FIG. 31Aillustrates the ratio of stray light intensity with respect to incidentlight intensity as contrast, in a case of rotation within the xy planewith the direction where the direction of the fast axis and thedirection of the x axis match as a reference (where the quarter phasedifference axis rotation angle=0°), and FIG. 31B in a case of rotationwithin the xy plane with the direction where the direction of the slowaxis and the direction of the x axis match as a reference (where thequarter phase difference axis rotation angle=0°). The clockwisedirection of the rotation angle of the quarter wave plate as viewed fromthe z positive direction is the positive direction, and thecounter-clockwise direction is the negative direction. The outermostangle of the incident illumination light here to the reflective liquidcrystal display device 11 b is 12°.

With the fast axis as the reference, the contrast is maximum at 3008when rotated −1.1° in the negative direction, and with the slow axis asthe reference, the contrast is maximum at 3006 when rotated +1.1° in thepositive direction. As for 0th order light, the contrast, i.e., straylight, is equal, and is not dependent on the disposing direction (fastaxis and slow axis direction) of the optical axis of the quarter waveplate 12 b.

Next, stray light of the diffracted light will be calculated. FIG. 32shows the diffraction angle of diffracted light of each order and thepolarization axis inclination of the polarization beam splitter 9 b.Here, the polarization axis inclination angle of the polarization beamsplitter 9 a is generated only for the diffracted light of theorientation angle 90° (x positive direction) and orientation angle 270°(x negative direction), and analyzing and transmission (stray light)occurs according to each polarization axis inclination angle.

FIGS. 33A and 33B illustrate the amount of stray light of diffractedlight in a case of the optical axis (fast axis and slow axis) of thequarter wave plate 12 b being rotated within the xy plane. Here, the sumof stray light of the diffracted light of the 1st order through the 5thorder is shown as the sum of diffraction stray light regarding eachorientation angle (0°, 90°, 180°, and 270°), and each diffracted lightintensity generated from the reflective liquid crystal display device 11b is represented as 1.

FIG. 33A illustrates a case where the fast axis is set with the xdirection as a reference, and FIG. 33B illustrates a case where the slowaxis is set with the x direction as a reference. It can be seen fromFIG. 33A that the minimum value of the sum of all diffracted stray lightis 0.208 with the fast axis inclined by −1.5°, and from FIG. 33B thatthe minimum value of the sum of all diffracted stray light is 0.042 withthe slow axis inclined by +1.5°. Thus, with the present exemplaryembodiment, the amount of diffraction stray light can be reduced toaround one fifth, and contrast can be improved, by placing the slow axisbased on the x direction, and further inclining by +1.5°.

Also, the sum of diffracted stray light in the orientation angle 0° and180° which is cast into the direction where there is no polarizationaxis inclination due to the polarization split film 9 b 1 of thepolarization beam splitter 9 b is 0.035 (FIG. 33A) when the fast axiscan be inclined −1.5° from the x axis direction, and is 0.035 (FIG. 33B)when the slow axis can be inclined +1.5° from the x axis direction,meaning that the contrast is not dependent on the optical axispositioning direction of the quarter wave plate 12 b (the direction ofthe fast axis or slow axis).

On the other hand, the sum of diffracted stray light in the orientationangle 90° and 270° which is cast into the direction where there ispolarization axis inclination due to the polarization split film 9 b 1of the polarization beam splitter 9 b is 0.173 (FIG. 33A) when the fastaxis can be inclined −1.5° from the x axis direction, and is 0.006 (FIG.33B) when the slow axis can be inclined +1.5° from the x axis direction,meaning that the contrast is dependent on the optical axis positioningdirection of the quarter wave plate 12 b (the direction of the fast axisor slow axis).

Keeping the generally-parallel angle between the slow axis direction ofthe quarter wave plate 12 b and the S-polarization direction within 5°yields images with high contrast, and keeping this within 3° yieldsimages with even higher contrast.

Second Exemplary Embodiment

FIG. 34 illustrates an overall diagram of a reflective liquid crystaldisplay apparatus which is the second exemplary embodiment. In thedrawing, components which are the same as those in FIG. 1 of the firstexemplary embodiment have been provided with the same referencenumerals.

In the drawing, reference numeral 301 denotes a one-dimensionalintegrator configured to form a substantially uniform intensityillumination distribution in a one-dimensional direction, configured ofa cylindrical lens arrays 301 a and 301 b arrayed one-dimensionally, and302 a and 302 b are light flux compression lenses for compressedillumination of the generally parallel light flux emitted from the lightsource 1, having curvature only with regard to the directionsubstantially orthogonal to the direction of array of the cylindricallens arrays 301 a and 301 b.

Further, the light flux from the illumination optical system issubjected to color separation into the three colors or R, G, and B,which are then cast into each of the reflective liquid crystal displaydevices 11 r, 11 g, and 11 b, and further synthesized and introduced tothe projection lens system 14. The configuration of such a colorseparating/synthesizing optical system is the same as that shown in FIG.12 for the first exemplary embodiment.

Now, the geometric-optical effects of the illumination optical systemaccording to the present exemplary embodiment will be described withreference to a two-dimensional cross-sectional diagram.

FIG. 35A illustrates a cross-sectional diagram in the lens arraydirection of the cylindrical lens arrays 301 a 1 and 301 b 1 (YZcross-sectional diagram). The Z-axial direction is the optical axisdirection of the light emitted from the light source 1 a, the Y-axialdirection is the direction of lens array of the one-dimensionalintegrator, and the X-axial direction is the direction substantiallyperpendicular to the YZ plane. Further, FIG. 35B is an XZcross-sectional diagram.

The one-dimensional integrator 301 a has a first cylindrical lens array301 a 1 made up of multiple cylindrical lenses having refractive powerin the YZ plane, and a second cylindrical lens array 301 b 1, and thecondensing optical system has the first optical compression lenses 301 a1 having refractive power in the XZ plane, a condenser lens 7 a formedof a spherical system, and the second light flux compression lenses 301b 1 having refractive power in the XZ plane.

The geometric optics occurring in the XZ plane shown in FIG. 35A will bedescribed. Light emitted from the light source 1 a is reflected off ofthe reflector 2 a and is cast into the first cylindrical lens array 301a 1 as generally parallel light. Light emitted from the firstcylindrical lens array 301 a 1 is divided according to the number oflenses in the lens array, and is condensed to form a light source imagenear the second cylindrical lens array 301 b 1. Light emitted from thesecond cylindrical lens array 301 b 1 is refracted by the positiverefractive power in the Y direction, and further is subjected to therefractive power of the condenser lens 7 a, and is cast into thereflective liquid crystal display device 11 g.

Further, the geometric optics occurring in the XZ plane shown in FIG.35B will be described. Light emitted from the light source 1 b isreflected off of the reflector 2 b and proceeds in the Z positivedirection as generally parallel light, is not subjected to therefractive power of the first cylindrical lens array 301 a 2 and thesecond cylindrical lens array 301 b 2, and illuminated in a condensedmanner on the reflective liquid crystal display device 11 g as generallyparallel light due to the light flux compression lenses 301 a 2 and 301b 2.

According to FIG. 35A, regarding light cast into the reflective liquidcrystal display device 11 g from the Y direction, the light flux emittedfrom the second cylindrical lens array 301 b 1 and the condenser lens 7a and then is illuminated on the reflective liquid crystal displaydevice 11 g in a superimposed manner having been subjected to refractivepower in the Y direction, and the incident angle is great and theintensity is great. On the other hand, according to FIG. 35B, regardinglight cast into the reflective liquid crystal display device 11 g fromthe X direction, the light flux emitted from the light flux compressinglenses 301 a 2 and 301 b 2 is illuminated on the reflective liquidcrystal display device 11 g in a compressed manner as generally parallellight, and the incident angle is small and the intensity is small.

The incident angle intensity distribution cast into the reflectiveliquid crystal display device 11 g is such that the angle of incidentlight from the S-polarization direction (Y direction) is great withgreat intensity, and the angle of incident light from the P-polarizationdirection (X direction) is small with small intensity (the intensity ofincident light of the S-polarization direction should be 1.3 times theintensity of incident light of the P-polarization direction, suitably1.7 times or greater intensity), yielding a rhombus-shaped distribution,and is a distribution with small angle of incident light from 45° (135°,215°, 315°) and weak intensity (the intensity of incident light of theS-polarization direction should be 1.2 times the intensity of incidentlight from 45°, suitably 1.4 times or greater intensity).

Now, FIG. 36 illiterates an example of incident angle intensitydistribution of light flux cast into the reflective liquid crystaldisplay device 11 by the illumination optical system according to thepresent exemplary embodiment. Here, the incident orientation angles areaccording to the coordinates system shown in FIG. 13 of the firstexemplary embodiment, where the orientation angle 0° means a beamentering from the y axis negative direction, the orientation angle 90°the x axis positive direction, the orientation angle 180° the y axispositive direction, and the orientation angle 270° the x axis negativedirection, respectively. It can be understood here that of the planesfollowing the orientation angles, the plane where the intensity of lightentering the reflective liquid crystal display device is greatest ingenerally parallel with the X axis (S-polarization direction), withoffset within 3°, and in at least one exemplary embodiment, within 1°.

Now, the angle distribution of stray light when the amount of straylight is minimal as shown in FIGS. 18A and 18B (incident lightintensity/amount of stray light is maximal) of the first exemplaryembodiment is shown in FIGS. 37A and 37B. Let us say that the incidentangle intensity distribution on the reflective liquid crystal displaydevice 11 g here is a flat illumination where the intensity is the samefor the tilt angles 0° through 12° over the orientation angles 0°through 360°. FIG. 37A shows the angle intensity distribution of straylight in a case where the fast axis of the quarter wave plate has beenrotated −0.9° from the x axis direction, and FIG. 37B a case where theslow axis of the quarter wave plate has been rotated +0.9° from the xaxis direction. Also, as for the value of stray light, the intensity ofthe total incident light flux is 1.

As can be seen from FIGS. 37A and 37B, there is a great amount of straylight at orientation angles 45° and 255° where the phase differenceerror of the reflective liquid crystal display device 11 g displayingblack as shown in FIG. 15 is great, and the stray light distribution isgenerally equal for both cases of basing on the fast axis and the slowaxis (FIGS. 37A and 37B).

Further, FIGS. 38A and 38B illustrate diagrams where the stray lightdistribution shown in FIGS. 37A and 37B has been weighted with theincident angle intensity distribution at the reflective liquid crystaldisplay device 11 g according to the present exemplary embodiment shownin FIG. 36. As with FIGS. 37A and 37B, for the value of stray light, theintensity of the total incident light flux is 1. Here, the intensity ofthe incident angle intensity distribution shown in FIG. 36 is weak inthe direction of the orientation angle 45° (135°, 225°, 315°), so straylight in the orientation angles 45° and 225° shown in FIG. 37A and 37Bdecreases, and the amount of stray light of the entire light flux can bereduced, and contrast can be improved.

FIG. 39A illustrates the ratio of stray light intensity with respect toincident light intensity as contrast, in a case of rotation within thexy plane with the direction where the direction of the fast axis and thedirection of the x axis match as a reference (where the quarter phasedifference axis rotation angle=0°), and FIG. 39B in a case of rotationwithin the xy plane with the direction where the direction of the slowaxis and the direction of the x axis match as a reference (where thequarter phase difference axis rotation angle=0°). The clockwisedirection of the rotation angle of the quarter wave plate as viewed fromthe z positive direction is the positive direction, and thecounter-clockwise direction is the negative direction.

As can be seen from FIGS. 39A and 39B, with the fast axis as thereference, the contrast is maximum at 4004 when rotated −0.9° in thenegative direction, and with the slow axis as the reference, thecontrast is maximum at 4005 when rotated +0.9° in the positivedirection. As for contrast of 0th order light (stray light), there is nodifference in performance according to the disposing direction (fastaxis and slow axis direction) of the optical axis of the quarter waveplate 12 g, and further, stray light can be reduced further than thecase shown in FIGS. 18A and 18B where flat illumination light is cast,so contrast can be improved.

Also, in the case of the reflective liquid crystal display device 11 gdisplaying black generating diffracted light having the phase differencepattern such as shown in FIG. 16 of the first exemplary embodiment,stray light such as shown in FIGS. 20A and 20B is generated. FIG. 20Aillustrates a case where the fast axis is set with the x direction as areference, and FIG. 20B illustrates a case where the slow axis is setwith the x direction as a reference. It can be seen from FIG. 20A thatthe minimum value of the sum of all diffracted stray light is 0.225 withthe fast axis inclined by −1.5°, and from FIG. 20B that the minimumvalue of the sum of all diffracted stray light is 0.045 with the slowaxis inclined by +1.5°. Thus, the amount of diffraction stray light canbe reduced to around one fifth, and contrast can be improved, by placingthe slow axis based on the x direction, and further inclining by +1.5°.

As described above, with the illumination optical system according tothe present exemplary embodiment, stray light of the 0th order light atthe reflective liquid crystal display device can be reduced, andfurther, setting the slow axis near the x axis direction facilitates thereduction of stray diffracted light generated at the reflective liquidcrystal display device, thus improving contrast.

Also, keeping the generally-parallel angle between the slow axisdirection of the quarter wave plate 12 g and the S-polarizationdirection within 5° yields images with high contrast, and keeping thiswithin 3° yields images with even higher contrast.

The reflective liquid crystal display apparatus according to theexemplary embodiments described above can be described as follows.

The reflective liquid crystal display apparatus according to the presentexemplary embodiment comprises: a polarization beam splitter having apolarization split film; a reflective liquid crystal display device; aquarter wave plate disposed between the polarization beam splitter andthe reflective liquid crystal display device; and an illuminationoptical system for guiding a light flux from a light source in aconverged state to the polarization beam splitter, and also illuminatingthe reflective liquid crystal display device with light from the lightsource via the polarization beam splitter and the quarter wave plate;where the optical axis of the illumination optical system can beinclined with respect to the polarization split film; and where, withthe positive phase difference provided to convert linear polarized lightinto right-handed circling polarized light or elliptic polarized lightand the negative phase difference provided to convert linear polarizedlight into left-handed circling polarized light or elliptic polarizedlight, the phase difference which the reflective liquid crystal displaydevice in a black display state of the reflective liquid crystal displayapparatus provides to the diffracted light occurring at the reflectiveliquid crystal display device is (1) positive or zero, (2) positive orzero, (3) negative or zero, (4) negative or zero; and where, with thepolarization direction of S-polarized light defined by the optical axisof the illumination optical system and the polarization split film asthe S-polarization direction, the polarization split film which receivesthe light flux in a converged state has a first region which emits lighthaving a polarization direction inclined clockwise with respect to theS-polarization direction as viewed from the side of the reflectiveliquid crystal display device, and a second region which emits lighthaving a polarization direction inclined counter-clockwise with respectto the S-polarization direction as viewed from the side of thereflective liquid crystal display device; and where the phasedifference, which the reflective liquid crystal display device providesto the first diffracted light emitted from a point on the optical axisof the reflective liquid crystal display device and cast into the firstregion, is (1) smaller, (2) greater, (3) smaller, (4) greater than thephase difference which the reflective liquid crystal display deviceprovides to the second diffracted light emitted from a point on theoptical axis of the reflective liquid crystal display device and castinto the second region; and where the quarter wave plate can bepositioned such that the direction of the (1) slow axis, (2) fast axis,(3) fast axis, (4) slow axis of the quarter wave plate and theS-polarization direction are generally parallel.

Light from the light source is cast into the polarization beam splitterand the quarter wave plate in that order, the light emitted form thequarter wave plate illuminates the reflective liquid crystal displaydevice, and the light reflected off of the reflective liquid crystaldisplay device passes through the quarter wave plate and thepolarization beam splitter and is input to the projection opticalsystem.

Also, the optical axis of the illumination optically system can beinclined with respect to the face of the polarization split film (thenormal line of the face of the polarization split film) at an angle of40° to 50°, and in at least one exemplary embodiment, 44.5° to 45.5°,and the light flux converged at the illumination optical system is castinto the polarization split face. Here, the light from the light sourceis divided into multiple light fluxes within the illumination opticalsystem, and each of the divided light fluxes is cast into thepolarization split face in the converged state.

Also, the aforementioned S-polarization direction is a direction definedby the optical axis of the illumination optical system, that is, definedby a beam traveling the optical axis of the illumination optical systemand the polarization split face (in other words, the polarizationdirection of S-polarization light at the time of the beam traveling theoptical axis of the illumination optical system being cast into thepolarization split face), and the direction substantially perpendicularto the S-polarization direction in a plane substantially perpendicularto the optical axis of the above illumination optical system is calledthe P-polarization direction.

It should be noted that black display refers to a state where lightinput to the reflective liquid crystal device is shielded from thedownstream optical systems (e.g., projection optical system, etc.), andthis can be shielded by absorption or by reflection. With the presentexemplary embodiment, the light is shielded by being reflected with thepolarization beam splitter. Of course, complete shielding of light castinto the reflective liquid crystal display device is impractical, so asmall amount of stray light is permissible. Also, arrangements wherelight is intentionally leaked during black display can be conceived.From a different perspective, the black display state is a state of thereflective liquid crystal display apparatus (reflective liquid crystaldisplay device) where the original image (the original image upon whichthe image to be displayed using the reflective liquid crystal displayapparatus is based upon) is solid black, and does not mean a state wherethe displayed image is solid black.

Also, the first region (the upper half region of the liquid crystaldisplay device 105 a in FIG. 1) is a region where, in the polarizationsplit face 103 a in FIG. 1, light is emitted having a polarizationdirection inclined in the clockwise direction as with 107 a with respectto the X axis when viewed from the reflective liquid crystal displaydevice 105 a side, and the second region (the lower half region of theliquid crystal display device 105 a in FIG. 1) is a region where, in thepolarization split face 103 a in FIG. 1, light is emitted having apolarization direction inclined in the counter-clockwise direction aswith 107 b with respect to the X axis when viewed from the reflectiveliquid crystal display device 105 a side.

Also, a description has been made where the quarter wave plate isdisposed such that the direction of the slow axis (fast axis) of thequarter wave plate and the S-polarization direction are generallyparallel; this term “generally parallel” meaning that the angle betweenthe two should be within 5°, and more suitably within 3°. In the case ofusing multiple reflective liquid crystal display devices, at least oneexemplary embodiment satisfies this condition. Also, in a case of usingthree reflective liquid crystal display devices (e.g., for the threewavelength regions of red, green, and blue), at least two should satisfythis condition, and regarding the two (e.g., liquid crystal displaydevice for the wavelength regions of red and green) and arrangements canbe made where the angle between the slow axis (fast axis) of the quarterwave plate and the S-polarization direction is within 2° (more suitablywithin 1)°, and the other (e.g., the liquid crystal display device forthe blue wavelength region) is within 5° (more suitably within 3)°.

This illumination optical system has a configuration where the focaldistance, total power, sum of positive power alone, sum of negativepower alone, etc., differ between two planes substantially orthogonallyintersecting with inclusion of the optical axis of the illuminationoptical system.

Multiple first lenses (e.g., cylindrical lenses having refractive poweressentially in the first direction, toric lenses having some refractivepower in the second direction substantially orthogonal to the firstdirection, other multiple lenses as known by one of ordinary skill inthe relevant art, and equivalents) are arrayed along the first directioncrossing the optical axis of the illumination optical system, andsuitably comprises a first integrator (cylindrical lens array, 3 a inFIG. 12) for dividing the light from the light source into multiplelight fluxes (along the first direction), a second integrator(cylindrical lens array, 3 b in FIG. 12) where multiple second lensesare disposed corresponding to the multiple first lenses, and a firstoptical system for irradiating the multiple optical fluxes emitted fromthe second integrator on the reflective liquid crystal display device ina superimposed manner (while irradiating a substantial portion of thelight fluxes so as to be superimposed one upon another, an arrangementwhere each light flux is guided to the reflective liquid crystal displaydevice in a manner overlapped with each other is permissible) withregard to the first direction (or a first plane including the firstdirection and the optical axis of the illumination optical system). Thearrangement can also have a second optical system having a seconddirection substantially orthogonal to the first direction, for guidingthe light flux from the light source to the reflective liquid crystaldisplay device with the diameter thereof reduced in a plane includingthe second direction. The second optical system suitably forms an afocalsystem with regard to the second direction (second plane including thesecond direction and the optical axis of the illumination opticalsystem), so with respect to guide the generally parallel light from thelight source to the reflective liquid crystal display device whilereducing the width thereof with regard to this second direction (secondplane).

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the discussed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so withrespect to encompass all modifications, equivalent structures andfunctions. For example, in the interest of acting as ones ownlexicographer, although the following claims may cite terms such as“perpendicular”, “orthogonal”, “vertical”, “horizontal”, the intendedmeaning of these terms within the scope of the claims is to includearrangements of “substantially perpendicular” or “essentiallyperpendicular”, “substantially orthogonal” or “essentially orthogonal”,“substantially vertical” or “essentially vertical”, and “substantiallyhorizontal” or “essentially horizontal.”

What is claimed is:
 1. A reflective liquid crystal display apparatuscomprising: a polarization beam splitter having a polarization splitfilm; a reflective liquid crystal display device; a quarter wave platedisposed between the polarization beam splitter and the reflectiveliquid crystal display device; and an illumination optical systemconfigured for guiding a light flux from a light source in a convergedstate to the polarization beam splitter, and also illuminating thereflective liquid crystal display device with light from the lightsource via the polarization beam splitter and the quarter wave plate,wherein an optical axis of the illumination optical system is inclinedwith respect to the polarization split film; wherein, with the positivephase difference provided to convert linear polarized light intoright-handed circling polarized light or elliptic polarized light andthe negative phase difference provided to convert linear polarized lightinto left-handed circling polarized light or elliptic polarized light,the phase difference which the reflective liquid crystal display devicein a black display state of the reflective liquid crystal displayapparatus provides to the diffracted light occurring at the reflectiveliquid crystal display device is positive or zero, wherein, with thepolarization direction of S-polarized light defined by the optical axisof the illumination optical system and the polarization split film asthe S-polarization direction, the polarization split film which receivesthe light flux in a converged state has a first region which emits lighthaving a polarization direction inclined clockwise with respect to theS-polarization direction as viewed from the side of the reflectiveliquid crystal display device, and a second region which emits lighthaving a polarization direction inclined counter-clockwise with respectto the S-polarization direction as viewed from the side of thereflective liquid crystal display device, wherein a cross-point is anintersection point of the optical axis of the illumination opticalsystem and the reflective liquid crystal display, wherein the phasedifference, which the reflective liquid crystal display device providesto the first diffracted light emitted from the cross-point and cast intothe first region, is greater than the phase difference which thereflective liquid crystal display device provides to the seconddiffracted light emitted from the cross-point and cast into the secondregion, and wherein the quarter wave plate can be positioned such thatthe direction of the fast axis of the quarter wave plate and theS-polarization direction are generally parallel.
 2. The apparatusaccording to claim 1, wherein, of the incident light flux from thepolarization beam splitter converging at the cross-point, with a planecontaining the polarization direction of S-polarized light defined bythe optical axis of the illumination optical system and the polarizationsplit film of the polarization beam splitter as the S-polarizationplane, and with a plane containing the polarization direction ofP-polarized light defined by the optical axis of the illuminationoptical system and the polarization split film of the polarization beamsplitter as the P-polarization plane, the intensity of incident lightcast into the reflective liquid crystal display device through theS-polarization plane is greater than the intensity of incident lightcast into the reflective liquid crystal display device through theP-polarization plane.
 3. The apparatus according to claim 1, wherein, ofthe incident light flux from the polarization beam splitter convergingat the cross-point, with a plane containing the polarization directionof S-polarized light defined by the optical axis of the illuminationoptical system and the polarization split film of the polarization beamsplitter as the S-polarization plane, and with a plane passing throughthe optical axis of the illumination optical system and assuming a 45°angle to the S-polarization plane as a 45° plane, the intensity ofincident light cast into the reflective liquid crystal display devicethrough the S-polarization plane is greater than the intensity ofincident light cast into the reflective liquid crystal display devicethrough the 45° plane.
 4. The apparatus according to claim 1, wherein,of the incident light flux from the polarization beam splitterconverging at the cross-point, with a plane containing the polarizationdirection of P-polarized light defined by the optical axis of theillumination optical system and the polarization split film of thepolarization beam splitter as the P-polarization plane, and with a planepassing through optical axis of the illumination optical system andassuming a 45° angle to the P-polarization plane as a 45° plane, theintensity of incident light cast into the reflective liquid crystaldisplay device through the P-polarization plane is greater than theintensity of incident light cast into the reflective liquid crystaldisplay device through the 45° plane.
 5. The apparatus according toclaim 1, further comprising: a first integrator, configured with aplurality of first lenses arrayed in a first direction intersecting theoptical axis of the illumination optical system, for splitting lightfrom the light source into a plurality of light fluxes; a secondintegrator wherein are arrayed a plurality of second lensescorresponding to the plurality of first lenses; a first optical systemconfigured for irradiating the plurality of light fluxes emitted fromthe second integrator on the reflective liquid crystal display device ina superimposed manner; and a second optical system having optical powerin a second direction orthogonal to the first direction, configured forcompressing the diameter of the light flux from the light source withina plane including the second direction, guided to the reflective liquidcrystal display device.